A Moiré pattern is formed when a first high frequency set of fringes is demodulated by means of a second high frequency set of fringes, the two frequencies having the same or similar values. The Moiré pattern is the low frequency pattern that results from the demodulation.
Moiré patterns may be classified as multiplicative or additive. A multiplicative Moiré pattern occurs when a function representing the pattern is formed as a product of two functions representing the fringes. An additive Moiré pattern is formed when a function representing the pattern is formed as a sum of two functions representing the fringes.
The prior art use of Moiré patterns for three-dimensional mapping of objects is based on contouring and thus is inherently plagued with ambiguity problems. An article entitled “Overview of three dimensional shape measurement using optical methods,” by F. Chen, et al., published in Optical Engineering Vol. 39, pages 10-22 (2000), features an overview of the use of Moiré patterns for three dimensional (3D) mapping. The article is incorporated herein by reference.
The description above is presented as a general overview of related art in this field and should not be construed as an admission that any of the information it contains constitutes prior art against the present patent application.